1. Field of the Invention
The present invention relates to a novel bottom anti-reflective coat forming composition which reduces reflection of exposure irradiation light from said substrate toward the photoresist layer coated over the substrate, and more particularly, to the bottom anti-reflective coat forming composition having the resin which effectively absorbs exposure irradiation light at the wave-length of 193 nm.
2. Description of the Related Art
The fine processing with lithography using the photoresist composition has been conducted for the preparation of semiconductor device heretofore. Said fine processing is the processing method comprising forming a film of the photoresist composition over silicon wafer, irradiating active light rays such as UV light through the mask pattern over which the pattern of semiconductor device has been drawn, developing and executing the etching treatment of silicon wafer of thus obtained resist pattern as the protective film. However, the higher degree of integration of semiconductor device has been achieved in recent years and active light rays used show tendency toward preferring short wave length from KrF excimer laser (248 nm) to ArF excimer laser (193 nm). Along with this progress, effects of irregular reflection and standing wave of active light rays from the substrate have become the major concern. Therefore, the method of providing the bottom anti-reflective coating between the photoresist and the substrate has been extensively investigated.
Inorganic bottom anti-reflective coating made of such as titanium, titanium dioxide, nitrided titanium, chrome oxide, carbon, α-silicon and the like, and organic bottom anti-reflective coating made of light absorbing material and polymer compound as the bottom anti-reflective coating are known. The former requires facilities such as vacuum deposition equipment, CVD device, spattering device and the like, while the latter is advantageous since the latter does not require any special facilities and therefore various investigations have been conducted. Examples of as such are acryl resin type bottom anti-reflective coating with hydroxyl group as crosslinking forming functional group and light absorbing group in the same molecule disclosed in U.S. Pat. No. 5,919,599 and novolac resin type bottom anti-reflective coating with hydroxyl group as crosslinking forming functional group and light absorbing group in the same molecule described in U.S. Pat. No. 5,693,691 among others.
According to the LSI pattern rule having the degree of fineness for less than 0.13 μm, the delay in wiring affects speeding up of LSI and thus advancing high-performance of LSI with the present technology for the production of LSI has become difficult. Therefore, Cu wiring material and the interlaminar insulating film with low dielectric constant are used in order to minimize the delay in wiring.
The desirable physical properties for the organic type bottom anti-reflective coating materials are having high absorbance against light or irradiation rays, absence of intermixing with resist layer (insoluble in resist solvent), no diffusion of small molecule into overcoating resist from the bottom anti-reflective coating material when applied or dried with heating, having large dry etching rate in comparison with resist and the like, and these are also described in for example Proc. SPIE, Vol. 3678, 174-185 (1999) or in Proc. SPIE, Vol. 2195, 225-229 (1994).
WO98/54619 discloses the bottom anti-reflective coat forming composition comprising the polymer which comprises acrylic acid ester structural unit containing blocked isocyanate group or isothiocyanate group as the essential ingredient and further maleimide or derivative thereof as an optional ingredient. When this polymer comprises maleimide or derivative thereof, 0.05 to 0.50 mol percent is said to be preferred.
JP Patent No. Hei 6-75378 discloses the bottom anti-reflective coat forming composition comprising the imide reaction product between at least one amino aromatic chromophore and the polymer having anhydride group. Said bottom anti-reflective coat forming composition comprises the polymer to which aromatic chromophore is bound through imide bond upon for example the reaction of copolymer of maleic acid anhydride and methacryl acid methyl with aminoanthracene and benzylamine.